Scroll compressor

ABSTRACT

The present disclosure relates to a scroll compressor. According to the present disclosure, in a shaft penetration scroll compressor in which an eccentric portion of the rotation shaft is overlapped with a orbiting wrap of the orbiting scroll in a radial direction, a back pressure chamber formed at a rear surface of the orbiting scroll may be eccentrically formed from the circular center around a discharge port to correspond to the eccentric discharge port, thereby effectively preventing tilting of the orbiting scroll due to the eccentricity of a gas force generated while the discharge port is eccentrically formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Korean Application No.10-2011-0098587, filed in Korea on Sep. 28, 2011 and Korean ApplicationNo. 10-2011-0098597, filed in Korea on Sep. 28, 2011, which is hereinexpressly incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

A scroll compressor is disclosed herein.

2. Description of the Related Art

Scroll compressor may include a fixed scroll having a fixed wrap and aorbiting scroll having a orbiting wrap. The scroll compressor provides amethod of inhaling and compressing refrigerant through a continuousvolume change of the compression chamber formed between the fixed wrapand the orbiting wrap while the orbiting scroll performs a circulatingmovement on the fixed scroll.

Furthermore, the scroll compressor continuously performs inhalation,compression and discharge, and thus has excellent characteristics in theaspect of vibration and noise generated during its operational processcompared to other types of compressors.

In a scroll compressor, the behavior characteristic is determined by itstype of the fixed wrap and orbiting wrap. The fixed wrap and orbitingwrap may have an arbitrary shape, but typically have an involute curvedshape that can be easily processed. The involute curve denotes a curvecorresponding to a trajectory drawn by a cross section of thread whenunloosing thread wound around a base circle having an arbitrary radius.When using such an involute curve, the capacity change rate is constantbecause a thickness of the wrap is constant and thus the number of turnsshould be increased to obtain a sufficient level of compression ratio,but it may also increase the size of the compressor.

On the other hand, the orbiting scroll is typically formed with a diskshaped end plate and the orbiting wrap at the side of the end plate.Furthermore, a boss portion is formed at a rear surface on which theorbiting wrap is not formed and connected to a rotation shaft forcirculating the orbiting scroll. Such a shape may form a orbiting wrapover a substantially overall area of the end plate, thereby decreasing adiameter of the end plate portion for obtaining the same compressionratio. However, on the contrary, the operating point to which arepulsive force of refrigerant is applied and the operating point towhich a reaction force for cancelling out the repulsive force is appliedare separated from each other in an axial direction, thereby causing aproblem of increasing vibration or noise while the orbiting scroll istilted during the operational process.

As a method for solving such problems, there has been disclosed aso-called shaft penetration scroll compressor which is a type that aposition at which the rotation shaft and the orbiting scroll arecombined with each other is formed on the same surface as the orbitingwrap. In such a type of compressor, the operating point of a repulsiveforce and the operating point of the reaction force are applied at thesame position, thereby solving a problem that the orbiting scroll isinclined.

However, in case of a shaft penetration scroll compressor as describedabove, a discharge port 11 of the orbiting scroll 1 is eccentricallyformed with respect to the center (Oo) of the orbiting scroll 1, andthus a back pressure chamber (S) may be formed between a rear surface ofthe orbiting scroll 1 and an upper frame 2 such that the center (Os) ofthe sealing members 31, 32 supporting the orbiting scroll 1 is disposedto be identical to the center (Oo) of the orbiting scroll 1 though a gasforce is eccentrically exerted, and as a result there has been a problemof causing tilting of the orbiting scroll 1 due to the eccentricity ofthe gas force. Undescribed reference numeral 4 in the drawing representsa fixed scroll, and reference numeral 5 represents an oldham ring.

SUMMARY OF THE INVENTION

An object of the present disclosure is to provide a scroll compressorcapable of preventing tilting of the orbiting scroll due to theeccentricity of a gas force in advance.

In order to accomplish the foregoing object, there is provided a scrollcompressor, including a fixed scroll having a fixed wrap; a orbitingscroll configured to have a orbiting wrap engaged with the fixed wrap toform a first and a second compression chamber at an inner surface and anouter surface thereof, and perform a orbiting with respect to the fixedscroll; a frame provided at an opposite side of the fixed scroll byinterposing the orbiting scroll to support the orbiting scroll; arotation shaft configured to have an eccentric portion at an end portionthereof, and combined with the orbiting scroll such that the eccentricportion is overlapped with the orbiting wrap in a radial direction; anda driving unit configured to drive the rotation shaft, wherein a backpressure chamber is formed between the orbiting scroll and the frame tosupport the orbiting scroll in the direction of the fixed scroll, andwhen a line connecting the center (Po) of the compression chamberimmediately prior to discharging compressed refrigerant from the firstcompression chamber and the second compression chamber to the geometriccenter (Oo) of the orbiting scroll is referred to as a first referenceline (L1), the back pressure chamber is formed such that the geometriccenter (So) of the back pressure chamber is located in a range of ±90°with respect to the first reference line (L1).

Furthermore, in order to accomplish the foregoing object, there isprovided a scroll compressor, including a fixed scroll having a fixedwrap; a orbiting scroll configured to have a orbiting wrap engaged withthe fixed wrap to form a first and a second compression chamber at aninner surface and an outer surface thereof, and perform a orbiting withrespect to the fixed scroll; a frame provided at an opposite side of thefixed scroll by interposing the orbiting scroll to support the orbitingscroll; a rotation shaft configured to have an eccentric portion at anend portion thereof, and combined with the orbiting scroll such that theeccentric portion is overlapped with the orbiting wrap in a radialdirection; and a driving unit configured to drive the rotation shaft,wherein a back pressure chamber is formed between the orbiting scrolland the frame to support the orbiting scroll in the direction of thefixed scroll, and the back pressure chamber is formed between aplurality of sealing members disposed to have a predetermined distancein a radial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a cross-sectional view illustrating a compression unit in ashaft penetration scroll compressor in the related art;

FIG. 2 is a plan view illustrating a back pressure chamber in acompression unit according to FIG. 1;

FIG. 3 is a cross-sectional view schematically illustrating the internalstructure of a scroll compressor according to an embodiment of thepresent disclosure;

FIG. 4 is a partial cross-sectional view illustrating a compression unitin the embodiment illustrated in FIG. 3;

FIG. 5 is an exploded perspective view illustrating a compression unitillustrated in FIG. 4;

FIGS. 6A and 6B are a plan view illustrating a first and a secondcompression chamber immediately subsequent to inhalation and immediatelyprior to discharge in a scroll compressor having a orbiting wrap and afixed wrap with an involute shape;

FIGS. 7A and 7B are a plan view illustrating a type of orbiting wrap ina scroll compressor having a orbiting wrap and a fixed wrap with anotherinvolute shape;

FIG. 8 is a plan view illustrating a orbiting wrap and a fixed wrapobtained by another envelope line;

FIG. 9 is an enlarged plan view illustrating a central portion thereofin FIG. 8;

FIG. 10 is a plan view illustrating a configuration in which theorbiting wrap is located prior to 150° starting discharge in theembodiment illustrated in FIG. 8;

FIG. 11 is a plan view illustrating a time point at which discharge isstarted from the second compression chamber in the embodimentillustrated in FIG. 8;

FIG. 12 is a cross-sectional view illustrating a compression unitaccording to the embodiment illustrated in FIG. 3;

FIG. 13 is a plan view illustrating an embodiment of the back pressurechamber in a compression unit according to FIG. 12;

FIG. 14 is a schematic view for explaining the location of a backpressure chamber according to FIG. 13;

FIG. 15 is a plan view illustrating another embodiment of the backpressure chamber in a compression unit according to FIG. 12; and

FIG. 16 is a schematic view for explaining the location of a backpressure chamber according to FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a scroll compressor according to the present disclosurewill be described in detail based on an embodiment illustrated in theaccompanying drawings.

Referring to FIG. 3, a scroll compressor according to the presentembodiment has a cylindrically shaped casing 110, and an upper shell 112and a lower shell 114 for covering an upper portion and a lower portionof the casing, respectively. The upper shell and lower shell may bebonded to the casing to form one confined space together with thecasing.

A discharge pipe 116 may be provided at an upper portion of the uppershell 112. The discharge pipe 116 corresponds to a path through whichcompressed refrigerant is discharged to the outside, and an oilseparator (not shown) for separating oil mixed with the dischargedrefrigerant may be connected to the discharge pipe 116. Furthermore, asuction pipe 118 is provided at a lateral surface of the casing 110. Asa path through which refrigerant to be compressed flows, the suctionpipe 118 is located at a boundary surface between the casing 110 and theupper shell 112 in FIG. 3, but the location may be set at discretion.Moreover, the lower shell 114 may also function as an oil chamber forstoring oil supplied to operate the compressor in an efficient manner.

A motor 120 as a driving unit may be provided at a substantially centralportion of the inner portion of the casing 110. The motor 120 mayinclude a stator 122 fixed to an inner surface of the casing 110 and arotor 124 located at an inner portion of the stator 122 to be rotated byan interaction with the stator 122. A rotation shaft 126 is combinedwith the center of the rotor 124 and rotated together with the rotor124.

An oil passage 126 a may be formed at an central portion of the rotationshaft 126 to be extended along a length direction of the rotation shaft126, and an oil pump 126 b for supplying oil stored in the lower shell114 to the upper portion thereof may be provided at a lower end portionof the rotation shaft 126. The oil pump 126 b may have a shape in whicha spiral groove is formed or a separate impeller is provided at an innerportion of the oil passage, and a separate capacity type pump may beprovided therein.

An enlarged diameter portion 126 c inserted into an inner portion of theboss portion formed on the fixed scroll which will be described latermay be formed at an upper end portion of the rotation shaft 126. Theenlarged diameter portion may be formed to have a diameter larger thanthe other portion thereof, and a pin portion 126 d forming an eccentricportion together with the eccentric bearing 128 which will be describedlater may be formed at an end portion of the enlarged diameter portion.The eccentric bearing 128 for forming an eccentric portion together withthe pin portion 126 d may be inserted into the pin portion 126 d, andreferring to FIG. 5, the eccentric bearing 128 may be eccentricallyinserted with respect to the pin portion 126 d, and a combining portionfor both may be asymmetrically formed in a substantially “D” shape basedon the center of the pin portion such that the eccentric bearing 128 isnot rotated with respect to the pin portion 126 d.

A fixed scroll 130 may be mounted on a boundary portion between thecasing 110 and upper shell 112. The fixed scroll 130 may be pushed andfixed between the casing 110 and the upper shell 112 in a shrink fitmanner or combined together with the casing 110 and upper shell 112 bywelding.

A boss portion 132 into which the foregoing rotation shaft 126 isinserted may be formed at a bottom surface of the fixed scroll 130. Apenetration hole through which the pin portion 126 d of the rotationshaft 126 passes may be formed at an upper side surface (based on FIG.3) of the boss portion 132 and thus the pin portion 126 d may beprotruded in the upward direction of the end plate portion 134 of thefixed scroll 130 therethrough.

A fixed wrap 136 engaged with the orbiting wrap which will be describedlater to form a compression chamber may be formed at an upper portionsurface of the end plate portion 134, and a space portion foraccommodating the orbiting scroll 140 which will be described later maybe formed, and a lateral wall portion 138 adjoining an innercircumferential surface of the casing 110 may be formed at an outercircumferential portion of the end plate portion 134. A orbiting scrollsupport portion 138 a on which an outer circumferential portion of theorbiting scroll 140 is placed may be formed at an inner side of theupper end portion of the lateral wall portion 138, and the height of theorbiting scroll support portion 138 a may be formed to have the sameheight as the fixed wrap 136 or to have a height slightly less than thatof the fixed wrap, and thus an end portion of the orbiting wrap can bebrought into contact with a surface of the end plate portion of thefixed scroll.

The orbiting scroll 140 may be provided at an upper portion of the fixedscroll 130. The orbiting scroll 140 may be formed with a substantiallycircular shaped end plate portion 142 and a orbiting wrap 144 engagedwith the fixed wrap 136. A substantially circular shaped rotation shaftcombining portion 146 rotatably inserted and fixed to the eccentricbearing 128 may be formed at a central portion of the end plate portion142. An outer circumferential portion of the rotation shaft combiningportion 146 may be connected to the orbiting wrap to perform the role offorming a compression chamber together with the fixed wrap during thecompression process. It will be described later.

On the other hand, the eccentric bearing 128 may be inserted into therotation shaft combining portion 146 and thus an end portion of therotation shaft 126 may be inserted through the end plate portion of thefixed scroll, and the orbiting wrap, fixed wrap and eccentric bearing128 may be provided to be overlapped with one another in the radialdirection of the compressor. During compression, a repulsive force ofrefrigerant may be applied to the fixed wrap and orbiting wrap, and acompression force may be applied between the rotation shaft supportportion and eccentric bearing as a reaction force thereto. As describedabove, when part of the shaft is overlapped with the wrap in a radialdirection through the end plate portion, the repulsive force andcompression force of refrigerant may be applied to the same surfacebased on the end plate, and thus they may be cancelled out by eachother. Due to this, it may be possible to prevent the inclination of theorbiting scroll by the operation of the compression force and repulsiveforce.

Furthermore, though not shown in the drawing, a discharge hole may beformed on the end plate portion 142 and thus compressed refrigerant maybe discharged to an inner portion of the casing. The location of thedischarge hole may be set at discretion by taking a required dischargepressure or the like into consideration.

Furthermore, an oldham ring 150 for preventing the rotation of theorbiting scroll may be provided at an upper side of the orbiting scroll140. The oldham ring 150 may include a substantially circular shapedring portion 152 inserted into a rear surface of the orbiting scroll 140and a pair of first key 154 and second key 156 which are protruded on alateral surface of the ring portion 152. The first key 154 may beprotruded farther than the thickness of an outer circumferential side ofthe end plate portion 142 of the orbiting scroll 140, and inserted intoan inner portion of the first key groove 154 a formed over an upper endof the lateral wall portion 138 of the fixed scroll 130 and the orbitingscroll support portion 138 a. Moreover, the second keys 156 may becombined with the second key grooves 156 a, respectively, formed at anouter circumferential portion of the end plate portion 142 of theorbiting scroll 140 in the state of being inserted therein.

Here, the first key groove 154 a may be formed to have a verticalportion extended in the upward direction and a horizontal portionextended in the left/right direction, and a lower side end portion ofthe first key 154 may always maintain a state of being inserted in thehorizontal portion of the first key groove 154 a, but an outer side endportion of the first key 154 in the radial direction may be formed to bereleased from the vertical portion of the first key groove 154 a duringthe circular movement of the orbiting scroll. In other words, a couplingbetween the first key groove 154 a and the fixed scroll may be made inthe vertical direction, thereby reducing the diameter of the fixedscroll.

Specifically, a clearance as much as corresponding to a circular radiusshould be secured between an end plate of the orbiting scroll and aninner wall of the fixed scroll. If a key of the oldham ring is combinedwith the fixed scroll in the radial direction, then the length of a keygroove formed on the fixed scroll should be at least greater than thecircular radius to prevent the oldham ring from being released from thekey groove during the circular process, and it may be a cause ofincreasing the size of the fixed scroll.

On the contrary, as in the above embodiment, if the key groove isextended to a lower space between the end plate and the orbiting wrap inthe orbiting scroll, it may be possible to secure a sufficient length ofthe key groove and reducing the size of the fixed scroll.

Moreover, in the above embodiment, all keys are formed at a lateralsurface of the ring portion, and thus the height of the compression unitin the axial direction can be reduced compared to a case that keys areformed, respectively, in both lateral surfaces thereof.

On the other hand, a lower frame 160 for rotatably supporting a lowerside of the rotation shaft 126 may be provided at a lower portion of thecasing 110, and the orbiting scroll and an upper frame 170 forsupporting the oldham ring 150 may be provided, respectively, at anupper portion of the orbiting scroll. A hole communicated with adischarge hole of the orbiting scroll 140 to discharge compressedrefrigerant to the side of the upper shell may be formed at the centerof the upper frame 170.

FIGS. 6A and 6B are a plan view illustrating a compression chamberimmediately subsequent to inhalation and a compression chamberimmediately prior to discharge in a scroll compressor having a orbitingwrap and a fixed wrap formed with an involute curve, and having aconfiguration that part of the shaft penetrates the end plate. FIG. 6Ais a view illustrating a change of the first compression chamber formedbetween an inner lateral surface of the fixed wrap and an outer lateralsurface of the orbiting wrap, and FIG. 6B is a view illustrating achange of the second compression chamber formed between an inner lateralsurface of the orbiting wrap and an outer lateral surface of the fixedwrap.

In the scroll compressor, the compression chamber may be created betweentwo contact points generated when the fixed wrap and orbiting wrap arebrought into contact with each other, and in case of the fixed wrap andorbiting wrap with an involute curve, two contact points defining onecompression chamber as illustrated in FIG. 4 may be located on astraight line. In other words, the compression chamber may be disposedover 360° with respect to the center of the rotation shaft.

Considering a volume change of the first compression chamber in FIG. 6A,the volume of the compression chamber immediately subsequent toinhalation located at the outside may be gradually reduced while movingto the central portion thereof by a circular movement of the orbitingscroll, and thus has a minimum value when reaching an outercircumferential portion of the rotation shaft combining portion locatedat the center of the orbiting scroll. In case of the fixed wrap andorbiting wrap with an involute curve, the volume reduction rate may belinearly reduced as increasing the rotation angle of the rotation shaft,and thus the compression chamber should be moved closely to the centerif possible, to obtain a high compression ratio, but in case where therotation shaft exists at the center as described above, it can be movedonly to an outer circumferential portion of the rotation shaft. Due tothis, the compression ratio may be reduced, and the compression ratio isabout 2.13 in FIG. 6A.

On the other hand, the second compression chamber illustrated in FIG. 6Bmay have a lower compression ratio compared to the first compressionchamber, and thus have a value of about 1.46. However, in case of thesecond compression chamber, when a connecting portion between therotation shaft combining portion (P) and the orbiting wrap is formedwith a circular arc shape as illustrated in FIG. 7A, a compression pathof the second compression chamber may be lengthened, thereby increasingthe compression ratio up to a level of 3.0. In this case, the secondcompression chamber may have a range of less than 360 degreesimmediately prior to discharge. However, such a method cannot beapplicable to the first compression chamber.

Accordingly, in case of the fixed wrap and orbiting wrap with aninvolute shape, an intentional level of compression ratio can beobtained in case of the second compression chamber, but it may beimpossible in case of the first compression chamber, and as a result, incase that there is a remarkable difference of compression ratio betweenthe two compression chambers, it will affect a bad effect on theoperation of the compressor.

In order to solve the foregoing problem, the fixed wrap and orbitingwrap may be formed to have another curve other than the involute curve.Referring to FIGS. 8 and 9, when the center of the rotation shaftcombining portion 146 is “O”, and two contact points are “P1, P2”,respectively, it is seen that an angle α defined by two straight linesconnecting the two contact points (P1, P2) to the center (O) of therotation shaft combining portion is less than 360°, and also a distance“I” between perpendicular vectors at each contact point has a valuegreater than “0”. Due to this, the first compression chamber immediatelyprior to discharge may have a volume less than a case of the fixed wrapand orbiting wrap formed with an involute curve, thereby increasing thecompression ratio. Furthermore, the orbiting wrap and fixed wrapillustrated in FIG. 8 may have a configuration in which the diameter andstarting point thereof are connected to a plurality of differentcircular arcs, and the outermost curve may have a substantially ovalshape having the major and minor axes.

Furthermore, a protrusion portion 137 protruded to the side of therotation shaft combining portion 146 may be formed adjacent to an innerside end portion of the fixed wrap, and a contact portion 137 a formedto be protruded from the protrusion portion may be additionally formedon the protrusion portion 137. In other words, the inner side endportion of the fixed wrap may be formed to have a thickness greater thanthe other portion thereof. Due to this, a strength of the inner side endportion of the wrap receiving the highest compression force on the fixedwrap can be enhanced, thereby enhancing the durability.

On the other hand, the thickness of the fixed wrap is graduallydecreased from the contact point (P1) located at an inner side betweenthe two contact points forming the first compression chamber at adischarge start time point as illustrated in FIG. 9. Specifically, afirst decreasing portion 137 b adjacent to the contact point (P1) and asecond decreasing portion 137 c adjacent to the first decreasing portionare formed, and a thickness reduction rate at the first decreasingportion may be greater than that at the second decreasing portion.Furthermore, the thickness of the fixed wrap may be increased for apredetermined section subsequent to the second decreasing portion.

Furthermore, when a distance between an inner surface of the fixed wrapand the axial center (O′) of the rotation shaft is DF, the DF may bedecreased after being increased as moving in a counter clockwisedirection (based on FIG. 9) from the P1, and the section thereof isshown in FIG. 10. FIG. 10 is a plan view illustrating the location ofthe orbiting wrap prior to 150° starting discharge, and the orbitingwrap may reach a configuration illustrated in FIG. 8 when the rotationshaft is further rotated by 150° from the configuration of FIG. 10.Referring to FIG. 10, the contact point is located at an upper side ofthe rotation shaft combining portion 146, and the DF may be increasedand then decreased during the section between P1 of FIG. 8 and P1 ofFIG. 10.

A concave portion 145 engaged with the protrusion portion may be formedat the rotation shaft combining portion 146. A lateral surface of theconcave portion 145 may be brought into contact with the contact portion137 a of the protrusion portion 137 to form a side contact point of thefirst compression chamber. When a distance between the center of therotation shaft combining portion 146 and an outer circumferentialportion of the rotation shaft combining portion 146 is “Do”, the “Do”may be increased and then decreased during the section between P1 ofFIG. 8 and P1 of FIG. 10. Similarly, the thickness of the rotation shaftcombining portion 146 may be also increased and then decreased duringthe section between P1 of FIG. 8 and P1 of FIG. 10.

Furthermore, a side wall of the concave portion 145 may include a firstincreasing portion 145 a in which the thickness thereof is drasticallyincreased in a relatively high rate and a second increasing portion 145b connected to the first increasing portion in which the thickness isincreased in a relatively low rate. They may correspond to the firstdecreasing portion and the second decreasing portion, respectively. Thefirst increasing portion, first decreasing portion, second increasingportion, and second decreasing portion are obtained as a result ofbending the envelope line toward the rotation shaft combining portion.Due to them, an inner side contact point (P1) forming the firstcompression chamber may be located at the first increasing portion andsecond increasing portion, and as a result, the compression ratio can beincreased by decreasing the length of the first compression chamberimmediately prior to discharge.

The other side wall of the concave portion 145 may be formed to have acircular arc shape. The diameter of the circular arc may be determinedby a wrap thickness of the end portion of the fixed wrap and a circularradius of the orbiting wrap, and the diameter of the circular arc may beincreased as increasing the thickness of the end portion of the fixedwrap. Due to this, the thickness of the orbiting wrap around thecircular arc may be also increased to secure the durability, and thecompression path may be lengthened and thus have an advantage ofincreasing the compression ratio of the second compression chamber asmuch as the lengthened path.

Here, a central portion of the concave portion 145 may form part of thesecond compression chamber. FIG. 11 is a plan view illustrating thelocation of the orbiting wrap when discharge is started from the secondcompression chamber, and the second compression chamber is locatedadjacent to a circular shaped side wall of the concave portion in FIG.11, and when the rotation shaft is further rotated, an end portion ofthe second compression chamber may pass through a central portion of theconcave portion.

On the other hand, in case of a shaft penetration scroll compressor asdescribed above, a gas force may be eccentrically exerted because thedischarge port is eccentrically formed with respect to the center of therotation shaft (or the circular center of the orbiting scroll), therebycausing tilting of the orbiting scroll due to the eccentricity of a gasforce. Taking this into account, according to the present embodiment,the back pressure chamber provided at an upper surface of the orbitingscroll may be eccentrically disposed around the center of the dischargeport by taking an eccentric level of the discharge port intoconsideration, and thus the discharge port may compensate theeccentricity of a gas force that can be eccentrically formed withrespect to the circular center of the orbiting scroll.

For example, as illustrated in FIGS. 12 and 13, a first sealing member181 and a second sealing member 182 may be provided between an uppersurface of the orbiting scroll 140 and a lower surface of the upperframe 170 corresponding thereto to have a predetermined distance in aradial direction to form the back pressure chamber (S) around thedischarge port 148.

To this end, a first sealing groove 149 a and a second sealing groove149 b may be formed on at least one side (an upper surface of theorbiting scroll in the present embodiment) of an upper surface of theorbiting scroll 140 and a lower surface of the upper frame 170 to allowthe first sealing member 181 and second sealing member 182,respectively, to be inserted therein. The first sealing groove 149 a andsecond sealing groove 149 b may be formed to correspond to the firstsealing member 181 and second sealing member 182.

The first sealing groove 149 a and second sealing groove 149 b may beformed in a ring shape, respectively, to allow the sealing members 181,182, respectively, to be inserted therein. Accordingly, across-sectional area of the back pressure chamber (S) formed by thefirst sealing member 181 and second sealing member 182 may be formed tobe identical along a radial direction.

Furthermore, the back pressure chamber (S) may be preferably formed suchthat a supporting force exerts in an opposite direction to the gas forcein an axial direction. In other words, as illustrated in FIG. 14, when aline connecting the center (Po) of the compression chamber immediatelyprior to discharge to the geometric center (Oo) of the orbiting scrollis referred to as a first reference line (L1), the back pressure chambermay be preferably formed such that the geometric center (So) of the backpressure chamber is located in a range of ±90° with respect to the firstreference line (L1) while at the same time located at the side at whichthe center (Po) of the final compression chamber is located with respectto the second reference line (L2).

According to a scroll compressor in accordance with the foregoingembodiment, refrigerant at high pressure discharged through thedischarge port 148 of the orbiting scroll 140 may flow into the backpressure chamber (S) to press and support the orbiting scroll 140 in thedirection of the fixed scroll with a pressure of the back pressurechamber (S).

At this time, the back pressure chamber (S) may be eccentrically formedfrom the geometric center (Oo) of the orbiting scroll as much as thedischarge port 148 is eccentrically located, thereby preventing theorbiting scroll 140 from being tilted by the eccentricity of a gas forcein advance. As a result, in a shaft penetration scroll compressor inwhich the rotation shaft 126 is combined and overlapped with a orbitingwrap 144 of the orbiting scroll 140 in a radial direction it may bepossible to prevent tilting of the orbiting scroll 140 due to theeccentricity of a gas force generated while the discharge port 148 iseccentrically formed with respect to the axial center of the rotationshaft 126, thereby enhancing the compressor performance.

On the other hand, according to the foregoing embodiment, the backpressure chamber may be formed to make a circular shape, but the backpressure chamber may be also formed in an oval shape. In other words,the back pressure chamber may be formed in an oval shape having a longaxis in the direction of the first reference line. Even in this case,the back pressure chamber may have a shape being moved in the directionof the discharge port compared to the related art, thereby reducingtilting of the orbiting scroll due to the eccentricity of a gas force tothe extent of the movement.

On the other hand, in case of a shaft penetration scroll compressor asdescribed above, a gas force is eccentrically exerted because thedischarge port is eccentrically formed with respect to the center of therotation shaft (or the circular center of the orbiting scroll), therebycausing tilting of the orbiting scroll due to the eccentricity of a gasforce. Taking this into account, according to the present embodiment,the back pressure chamber provided at an upper surface of the orbitingscroll may be eccentrically disposed around the center of the dischargeport by taking an eccentric level of the discharge port intoconsideration, and thus the discharge port may compensate theeccentricity of a gas force that can be eccentrically formed withrespect to the circular center of the orbiting scroll.

For example, as illustrated in FIGS. 12 and 15, a first sealing member181 and a second sealing member 182 may be provided between an uppersurface of the orbiting scroll 140 and a lower surface of the upperframe 170 corresponding thereto to have a predetermined distance in aradial direction to form the back pressure chamber (S) around thedischarge port 148.

To this end, a first sealing groove 149 a and a second sealing groove149 b may be formed on at least one side (an upper surface of theorbiting scroll in the present embodiment) of an upper surface of theorbiting scroll 140 and a lower surface of the upper frame 170 to allowthe first sealing member 181 and second sealing member 182,respectively, to be inserted therein. The first sealing groove 149 a andsecond sealing groove 149 b may be formed to correspond to the firstsealing member 181 and second sealing member 182.

For the first sealing member 181 and 182, a cross-sectional area of theback pressure chamber (S) formed by the first sealing member 181 andsecond sealing member 182 may be formed to be identical along a radialdirection, but according to circumstances, a cross-sectional area of theback pressure chamber (S) may be also formed to be different along aradial direction.

Either one side sealing member between the first sealing member 181 andsecond sealing member 182 may be formed in a ring shape whereas theother side sealing member may be formed in a non-circular shape. Here,as illustrated in FIG. 16, when a line connecting the center (Po) of thecompression chamber immediately prior to discharge to the geometriccenter (Oo) of the orbiting scroll is referred to as a first referenceline (L1), and a line perpendicular to the first reference line (L1)passing through the geometric center (Oo) of the orbiting scroll isreferred to as a second reference line (L2), the non-circular shapedsealing member (the first sealing member and the second sealing memberare formed in a similar shape in FIG. 16) may be preferably formed to besymmetric with respect to the first reference line (L1) and secondreference line (L2), respectively, thereby providing a uniform backpressure to the orbiting scroll.

Furthermore, the back pressure chamber (S) may be formed such that thegeometric center (So) of the back pressure chamber is identical to thegeometric center (Oo) of the orbiting scroll, but preferably formed suchthat a supporting force exerts in an opposite direction to the gas forcein an axial direction. In other words, as illustrated in FIG. 16, theback pressure chamber may be preferably formed such that the geometriccenter (So) of the back pressure chamber is located in a range of ±90°with respect to the first reference line (L1) while at the same timelocated at the side at which the center (Po) of the final compressionchamber is located with respect to the second reference line (L2).

To this end, both the first sealing member 181 and second sealing member182 may be formed in a ring shape and thus eccentrically disposed to theside of the discharge port 148, but at least either one side sealingmember between the first sealing member 181 and second sealing member182 (both sealing members are formed in a non-circular shape in FIG. 15)may be formed in a non-circular shape and thus the back pressure chamber(S) may be eccentrically disposed to the side of the discharge port 148.

In this case, the non-circular sealing member may be formed in a peanutshape with a wide discharge port and a narrow opposite side thereof. Asa result, the back pressure chamber can be controlled to be located in asufficiently eccentric manner without disposing the first sealing member181 and second sealing member 182 in an excessively eccentric manner.

According to a scroll compressor in accordance with the foregoingembodiment, refrigerant at high pressure discharged to the casing 110through the discharge port 148 of the orbiting scroll 140 may flow intothe back pressure chamber (S) to press and support the orbiting scroll140 in the direction of the fixed scroll with a pressure of the backpressure chamber (S).

At this time, the back pressure chamber (S) may be eccentrically formedfrom the geometric center (Oo) of the orbiting scroll as much as thedischarge port 148 is eccentrically located, thereby preventing theorbiting scroll 140 from being tilted by the eccentricity of a gas forcein advance. As a result, in a shaft penetration scroll compressor inwhich the rotation shaft 126 is combined and overlapped with a orbitingwrap 144 of the orbiting scroll 140 in a radial direction, the dischargeport 148 it may be possible to prevent tilting of the orbiting scroll140 due to the eccentricity of a gas force generated while the dischargeport 148 is eccentrically formed with respect to the axial center of therotation shaft 126, thereby enhancing the compressor performance.

On the other hand, according to the foregoing embodiment, a sealingmember constituting the back pressure chamber may be a non-circularshape, but both sides thereof may be formed to make a substantiallycircular shape or both sides of the back pressure chamber may be alsoformed to make an oval shape. In other words, both sides of the sealingmember may be formed in an oval shape having a long axis in thedirection of the first reference line, respectively. Even in this case,the back pressure chamber may have a shape being moved in the directionof the discharge port compared to the related art, thereby reducingtilting of the orbiting scroll due to the eccentricity of a gas force tothe extent of the movement.

What is claimed is:
 1. A scroll compressor, comprising: a fixed scrollhaving a fixed wrap; a orbiting scroll configured to have a orbitingwrap engaged with the fixed wrap to form a first and a secondcompression chamber at an inner surface and an outer surface thereof,and perform a orbiting with respect to the fixed scroll; a frameprovided at an opposite side of the fixed scroll by interposing theorbiting scroll to support the orbiting scroll; a rotation shaftconfigured to have an eccentric portion at an end portion thereof, andcombined with the orbiting scroll such that the eccentric portion isoverlapped with the orbiting wrap in a radial direction; and a drivingunit configured to drive the rotation shaft, wherein a back pressurechamber is formed between the orbiting scroll and the frame to supportthe orbiting scroll in the direction of the fixed scroll, and when aline connecting the center (Po) of the compression chamber immediatelyprior to discharging compressed refrigerant from the first compressionchamber and the second compression chamber to the geometric center (Oo)of the orbiting scroll is referred to as a first reference line (L1),the back pressure chamber is formed such that the geometric center (So)of the back pressure chamber is located in a range of ±90° with respectto the first reference line (L1).
 2. The scroll compressor of claim 1,wherein when a line perpendicular to the first reference line (L1)passing through the geometric center (Oo) of the orbiting scroll isreferred to as a second reference line (L2), the geometric center (So)of the back pressure chamber is formed at the side at which the center(Po) of the final compression chamber is located with respect to thesecond reference line (L2).
 3. The scroll compressor of claim 1, whereinthe back pressure chamber is formed between a plurality of sealingmembers disposed to have a predetermined distance in a radial direction,and a cross-sectional area of the back pressure chamber between theplurality of sealing members is formed to be identical along a radialdirection.
 4. The scroll compressor of claim 1, wherein the backpressure chamber is formed between a plurality of sealing membersdisposed to have a predetermined distance in a radial direction, and atleast one side of the sealing member among the plurality of sealingmembers is formed in a non-circular shape.
 5. The scroll compressor ofclaim 1, wherein the first compression chamber is formed between twocontact points (P1, P2) generated when an inner surface of the fixedwrap and an outer surface of the orbiting wrap are brought into contactwith each other, and when an angle having a greater value between anglesmade by two lines connecting the center (O) of the eccentric portion tothe two contact points (P1, P2), respectively, is α, α<360° at leastprior to starting discharge.
 6. The scroll compressor of claim 5,wherein when a distance between perpendiculars at the two contact points(P1, P2) is I, I>0.
 7. The scroll compressor of claim 1, wherein arotation shaft combining portion combined with the eccentric portion atan inner portion thereof is formed at a central portion of the orbitingscroll, and a protrusion portion is formed at an inner circumferentialsurface of an inner end portion of the fixed wrap, and a concave portionbrought into contact with the protrusion portion to form a compressionchamber is formed at an outer circumferential surface of the rearsurface combining portion.
 8. A scroll compressor, comprising: a fixedscroll having a fixed wrap; a orbiting scroll configured to have aorbiting wrap engaged with the fixed wrap to form a first and a secondcompression chamber at an inner surface and an outer surface thereof,and perform a orbiting with respect to the fixed scroll; a frameprovided at an opposite side of the fixed scroll by interposing theorbiting scroll to support the orbiting scroll; a rotation shaftconfigured to have an eccentric portion at an end portion thereof, andcombined with the orbiting scroll such that the eccentric portion isoverlapped with the orbiting wrap in a radial direction; and a drivingunit configured to drive the rotation shaft, wherein a back pressurechamber is formed between the orbiting scroll and the frame to supportthe orbiting scroll in the direction of the fixed scroll, and the backpressure chamber is formed between a plurality of sealing membersdisposed to have a predetermined distance in a radial direction.
 9. Thescroll compressor of claim 8, wherein a cross-sectional area of the backpressure chamber between the plurality of sealing members is formed tobe identical along a radial direction.
 10. The scroll compressor ofclaim 8, wherein the back pressure chamber is formed in a non-circularshape.
 11. The scroll compressor of claim 10, wherein a cross-sectionalarea of the back pressure chamber in a radial direction is formed to bedifferent along the radial direction.
 12. The scroll compressor of claim8, wherein at least one side of the sealing member among the pluralityof sealing members is formed in a non-circular shape.
 13. The scrollcompressor of claim 8, wherein when a line connecting the center (Po) ofthe compression chamber immediately prior to discharging compressedrefrigerant from the first compression chamber and the secondcompression chamber to the geometric center (Oo) of the orbiting scrollis referred to as a first reference line (L1), the back pressure chamberis formed such that the geometric center (So) of the back pressurechamber is located in a range of ±90° with respect to the firstreference line (L1).
 14. The scroll compressor of claim 13, wherein whena line perpendicular to the first reference line (L1) passing throughthe geometric center (Oo) of the orbiting scroll is referred to as asecond reference line (L2), the geometric center (So) of the backpressure chamber is formed at the side at which the center (Po) of thefinal compression chamber is located with respect to the secondreference line (L2).
 15. The scroll compressor of claim 8, wherein thefirst compression chamber is formed between two contact points (P1, P2)generated when an inner surface of the fixed wrap and an outer surfaceof the orbiting wrap are brought into contact with each other, and whenan angle having a greater value between angles made by two linesconnecting the center (O) of the eccentric portion to the two contactpoints (P1, P2), respectively, is α, α<360° at least prior to startingdischarge.
 16. The scroll compressor of claim 15, wherein when adistance between perpendiculars at the two contact points (P1, P2) is I,I>0.
 17. The scroll compressor of claim 8, wherein a rotation shaftcombining portion combined with the eccentric portion at an innerportion thereof is formed at a central portion of the orbiting scroll,and a protrusion portion is formed at an inner circumferential surfaceof an inner end portion of the fixed wrap, and a concave portion broughtinto contact with the protrusion portion to form a compression chamberis formed at an outer circumferential surface of the rear surfacecombining portion.